Wireless Digital Audio Music System

ABSTRACT

A wireless digital audio system includes a portable audio source with a digital audio transmitter operatively coupled thereto and an audio receiver operatively coupled to a headphone set. The audio receiver is configured for digital wireless communication with the audio transmitter. The digital audio receiver utilizes fuzzy logic to optimize digital signal processing. Each of the digital audio transmitter and receiver is configured for code division multiple access (CDMA) communication. The wireless digital audio system allows private audio enjoyment without interference from other users of independent wireless digital transmitters and receivers sharing the same space.

This continuation application claims the benefit of U.S. patentapplication Ser. No. 13/775,754 filed Feb. 25, 2013, which is acontinuation application claiming benefit of U.S. patent applicationSer. No. 13/356,949 filed Jan. 24, 2012, which was a continuationapplication claiming the benefit of U.S. patent application Ser. No.12/940,747 filed Nov. 5, 2010, now U.S. Pat. No. 8,131,391, which was acontinuation application claiming the benefit of U.S. patent applicationSer. No. 12/570,343 filed Sep. 30, 2009, now U.S. Pat. No. 7,865,258,which was a continuation claiming the benefit of U.S. patent applicationSer. No. 12/144,729 filed Jul. 12, 2008, now U.S. Pat. No. 7,684,885,which was a continuation claiming benefit of U.S. patent applicationSer. No. 10/648,012 filed Aug. 26, 2003, now U.S. Pat. No. 7,412,294,which was a continuation-in-part claiming benefit from U.S. patentapplication Ser. No. 10/027,391, filed Dec. 21, 2001, for “WirelessDigital Audio System,” published under US 2003/0118196 A1 on Jun. 26,2003, now abandoned, the disclosures of which are incorporated herein intheir entireties by reference.

BACKGROUND OF THE INVENTION

This invention relates to audio player devices and more particularly tosystems that include headphone listening devices. The new audio systemuses an existing headphone jack (i.e., this is the standard analogheadphone jack that connects to wired headphones) of a music audioplayer (i.e., portable CD player, portable cassette player, portableA.M./F.M. radio, laptop/desktop computer, portable MP3 player, and thelike) to connect a battery powered transmitter for wireless transmissionof a signal to a set of battery powered receiving headphones.

Use of audio headphones with audio player devices such as portable CDplayers, portable cassette players, portable A.M./F.M. radios,laptop/desktop computers, portable MP3 players and the like have been inuse for many years. These systems incorporate an audio source having ananalog headphone jack to which headphones may be connected by wire.

There are also known wireless headphones that may receive A.M. and F.M.radio transmissions. However, they do not allow use of a simple plug in(i.e., plug in to the existing analog audio headphone jack) batterypowered transmitter for connection to any music audio player devicejack, such as the above mentioned music audio player devices, for codedwireless transmission and reception by headphones of audio music forprivate listening without interference where multiple users occupyingthe same space are operating wireless transmission devices. Existingaudio systems make use of electrical wire connections between the audiosource and the headphones to accomplish private listening to multipleusers.

There is a need for a battery powered simple connection system forexisting music audio player devices (i.e., the previously mentionedmusic devices), to allow coded digital wireless transmission (using abattery powered transmitter) to a headphone receiver (using a batterypowered receiver headphones) that accomplishes private listening tomultiple users occupying the same space without the use of wires.

SUMMARY OF THE INVENTION

The present invention is generally directed to a wireless digital audiosystem for coded digital transmission of an audio signal from any audioplayer with an analog headphone jack to a receiver headphone locatedaway from the audio player. Fuzzy logic technology may be utilized bythe system to enhance bit detection. A battery-powered digitaltransmitter may include a headphone plug in communication with anysuitable music audio source. For reception, a battery-powered headphonereceiver may use embedded fuzzy logic to enhance user code bitdetection. Fuzzy logic detection may be used to enhance user code bitdetection during decoding of the transmitted audio signal. The wirelessdigital audio music system provides private listening withoutinterference from other users or wireless devices and without the use ofconventional cable connections.

These and other features, aspects and advantages of the presentinvention will become better understood with reference to the followingdrawings, description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

Some aspects of the present invention are generally shown by way ofreference to the accompanying drawings in which:

FIG. 1 schematically illustrates a wireless digital audio system inaccordance with the present invention;

FIG. 2 is a block diagram of an audio transmitter portion of thewireless digital audio system of FIG. 1.;

FIG. 3 is a block diagram of an audio receiver portion of the wirelessdigital audio system of FIG. 1; and

FIG. 4 is an exemplary graph showing the utilization of an embeddedfuzzy logic coding algorithm according to one embodiment of the presentinvention.

DETAILED DESCRIPTION

The following detailed description is the best currently contemplatedmodes for carrying out the invention. The description is not to be takenin a limiting sense, but is made merely for the purpose of illustratingthe general principles of the invention.

Referring to FIGS. 1 through 3, a wireless digital audio music system 10may include a battery powered transmitter 20 connected to a portablemusic audio player or music audio source 80. The battery poweredwireless digital audio music transmitter 20 utilizes an analog todigital converter or ADC 32 and may be connected to the music audiosource 80 analog headphone jack 82 using a headphone plug 22. Thebattery powered transmitter 20 may have a transmitting antenna 24 thatmay be omni-directional for transmitting a spread spectrum modulatedsignal to a receiving antenna 52 of a battery powered headphone receiver50. The battery powered receiver 50 may have headphone speakers 75 inheadphones 55 for listening to the spread spectrum demodulated anddecoded communication signal. In the headphone receiver 50, fuzzy logicdetection may be used to optimize reception of the received user code.The transmitter 20 may digitize the audio signal using ADC 32. Thedigitized signal may be processed downstream by an encoder 36. Afterdigital conversion, the digital signal may be processed by a digital lowpass filter. To reduce the effects of channel noise, the battery poweredtransmitter 20 may use a channel encoder 38. A modulator 42 modulatesthe digital signal to be transmitted. For further noise immunity, aspread spectrum DPSK (differential phase shift key) transmitter ormodule 48, is utilized. The battery powered transmitter 20 may contain acode generator 44 that may be used to create a unique user code. Theunique user code generated is specifically associated with one wirelessdigital audio system user, and it is the only code recognized by thebattery powered headphone receiver 50 operated by a particular user. Theradio frequency (RF) spectrum utilized (as taken from the Industrial,Scientific and Medical (ISM) band) may be approximately 2.4 GHz. Thepower radiated by the transmitter adheres to the ISM standard.

Particularly, the received spread spectrum signal may be communicated toa 2.4 GHz direct conversion receiver or module 56. Referring to FIGS. 1through 4, the spread spectrum modulated signal from transmit antenna 24may be received by receiving antenna 52 and then processed by spreadspectrum direct conversion receiver or module 56 with a receiver codegenerator 60 that contains the same transmitted unique code, in thebattery powered receiver 50 headphones. The transmitted signal fromantenna 24 may be received by receiving antenna 52 and communicated to awideband bandpass filter (BPF). The battery powered receiver 50 mayutilize embedded fuzzy logic 61 (as graphically depicted in FIGS. 1, 4)to optimize the bit detection of the received user code. The downconverted output signal of direct conversion receiver or module 56 maybe summed by receiver summing element 58 with a receiver code generator60 signal. The receiver code generator 60 may contain the same uniquewireless transmission of a signal code word that was transmitted byaudio transmitter 20 specific to a particular user. Other code wordsfrom wireless digital audio systems 10 may appear as noise to audioreceiver 50. This may also be true for other device transmitted wirelesssignals operating in the wireless digital audio spectrum of digitalaudio system 10. This code division multiple access (CDMA) may be usedto provide each user independent audible enjoyment. The resulting summeddigital signal from receiving summary element 58 and direct conversionreceiver or module 56 may be processed by a 64-Ary demodulator 62 todemodulate the signal elements modulated in the audio transmitter 20. Ablock de-interleaver 64 may then decode the bits of the digital signalencoded in the block interleaver 40. Following such, a Viterbi decoder66 may be used to decode the bits encoded by the channel encoder 38 inaudio transmitter 20. A source decoder 68 may further decode the codingapplied by encoder 36.

Each receiver headphone 50 user may be able to listen (privately) tohigh fidelity audio music, using any of the audio devices listedpreviously, without the use of wires, and without interference from anyother receiver headphone 50 user, even when operated within a sharedspace. The fuzzy logic detection technique 61 used in the receiver 50could provide greater user separation through optimizing code divisionin the headphone receiver.

The battery powered transmitter 20 sends the audio music information tothe battery powered receiver 50 in digital packet format. These packetsmay flow to create a digital bit stream rate less than or equal to 1.0Mbps.

The user code bits in each packet may be received and detected by afuzzy logic detection sub-system 61 (as an option) embedded in theheadphone receiver 50 to optimize audio receiver performance. For eachconsecutive packet received, the fuzzy logic detection sub-system 61 maycompute a conditional density with respect to the context and fuzzinessof the user code vector, i.e., the received code bits in each packet.Fuzziness may describe the ambiguity of the high (1)/low (0 or −1) eventin the received user code within the packet. The fuzzy logic detectionsub-system 61 may measure the degree to which a high/low bit occurs inthe user code vector, which produces a low probability of bit error inthe presence of noise. The fuzzy logic detection sub-system 61 may use aset of if-then rules to map the user code bit inputs to validationoutputs. These rules may be developed as if-then statements.

Fuzzy logic detection sub-system 61 in battery-powered headphonereceiver 50 utilizes the if-then fuzzy set to map the received user codebits into two values: a low (0 or −1) and a high (1). Thus, as the usercode bits are received, the “if” rules map the signal bit energy to thefuzzy set low value to some degree and to the fuzzy set high value tosome degree. FIG. 4 graphically shows that x-value −1 equals the maximumlow bit energy representation and x-value 1 equals the maximum high bitenergy representation. Due to additive noise, the user code bit energymay have some membership to a low and high as represented in FIG. 4. Theif-part fuzzy set may determine if each bit in the user code, for everyreceived packet, has a greater membership to a high bit representationor a low bit representation. The more a user code bit energy fits intothe high or low representation, the closer its subsethood, i.e., ameasure of the membership degree to which a set may be a subset ofanother set, may be to one.

The if-then rule parts that make up the fuzzy logic detection sub-system61 must be followed by a defuzzifying operation. This operation reducesthe aforementioned fuzzy set to a bit energy representation (i.e., −1or 1) that is received by the transmitted packet. Fuzzy logic detectionsub-system 61 may be used in battery-powered headphone receiver 50 toenhance overall system performance.

The next step may process the digital signal to return the signal toanalog or base band format for use in powering speaker(s) 75. Adigital-to-analog converter 70 (DAC) may be used to transform thedigital signal to an analog audio signal. An analog low pass filter 72may be used to filter the analog audio music signal to pass a signal inthe approximate 20 Hz to 20 kHz frequency range and filter otherfrequencies. The analog audio music signal may then be processed by apower amplifier 74 that may be optimized for powering headphone speakers75 to provide a high quality, low distortion audio music for audibleenjoyment by a user wearing headphones 55. A person skilled in the artwould appreciate that some of the embodiments described hereinabove aremerely illustrative of the general principles of the present invention.Other modifications or variations may be employed that are within thescope of the invention. Thus, by way of example, but not of limitation,alternative configurations may be utilized in accordance with theteachings herein. Accordingly, the drawings and description areillustrative and not meant to be a limitation thereof.

Moreover, all terms should be interpreted in the broadest possiblemanner consistent with the context. In particular, the terms “comprises”and “comprising” should be interpreted as referring to elements,components, or steps in a non-exclusive manner, indicating that thereferenced elements, components, or steps may be present, or utilized,or combined with other elements, components, or steps that are notexpressly referenced. Thus, it is intended that the invention cover allembodiments and variations thereof as long as such embodiments andvariations come within the scope of the appended claims and theirequivalents.

1. A wireless digital audio spread spectrum receiver, capable of mobileoperation, configured to receive a unique user code and an audio signalrepresentation from a digital audio spread spectrum transmitter, saidaudio signal representation representative of audio from a portableaudio source, said digital audio spread spectrum receiver operative tocommunicate wirelessly with said digital audio spread spectrumtransmitter, said digital audio spread spectrum receiver comprising: adirect conversion module configured to receive wireless spread spectrumsignal transmissions representative of the unique user code and theaudio signal representation, wherein the received transmissions areencoded to reduce intersymbol interference; a digital demodulatorconfigured to demodulate a received transmission and to generate ademodulated transmission, the digital demodulator configured to performfirst demodulation and second demodulation, wherein said seconddemodulation is differential phase shift keying (DPSK) demodulation; adecoder operative to decode the demodulated transmission and to generatea receiver audio signal representation, the decoder configured to decodereduced intersymbol interference coding and to decode representations ofaudio in the frequency range of 20 Hz to 20 kHz, said decoding beingseparate from said first and second demodulation; a digital-to-analogconverter (DAC) configured to generate an audio output from saidreceiver audio signal representation; and a speaker configured toreproduce said generated audio output, wherein said reproduction doesnot include audible audio content originating from any transmitted audiosignals in the wireless digital audio spread spectrum transmitterspectrum that do not originate from said digital audio spread spectrumtransmitter; wherein the wireless digital audio spread spectrum receiveris configured to use independent code division multiple accesscommunication and to use the received unique user code to communicateonly with said wireless digital audio spread spectrum transmitter forthe duration of a wireless connection.
 2. The wireless digital audiospread spectrum receiver of claim 1, wherein said audio from saidportable audio source is music.
 3. A portable spread spectrum audioreceiver, configured to receive and store a unique user code, saidportable spread spectrum receiver configured to receive wirelesstransmissions from a spread spectrum transmitter, said wirelesstransmissions representative of an audio signal representation, saidportable spread spectrum audio receiver comprising: a direct conversionmodule configured to receive wireless transmissions representative ofthe audio signal representation, wherein the received wirelesstransmissions are encoded to reduce intersymbol interference; a digitaldemodulator configured to demodulate a received transmission and togenerate a demodulated transmission, the digital demodulator configuredto perform first demodulation and second demodulation, wherein saidsecond demodulation is differential phase shift keying (DPSK)demodulation; a decoder operative to decode the demodulated transmissionand to generate a receiver audio signal representation, the decoderconfigured to decode reduced intersymbol interference coding and todecode representations of audio in the frequency range of 20 Hz to 20kHz, said decoding being separate from said first and seconddemodulation; a digital-to-analog converter (DAC) configured to generatean audio output from said receiver audio signal representation; and aspeaker configured to reproduce said generated audio output, whereinsaid reproduction does not include audible audio content originatingfrom any transmitted audio signals in the spread spectrum transmitterspectrum that do not originate from said spread spectrum transmitter;wherein the portable spread spectrum audio receiver is configured to useindependent code division multiple access communication and to use thereceived unique user code to communicate only with said spread spectrumtransmitter for the duration of a wireless connection.
 4. The portablespread spectrum receiver of claim 3, wherein the audio signalrepresentation represents music.
 5. A wireless digital coded audiospread spectrum transmitter operatively coupled to a portable audioplayer and configured to transmit a unique user code and arepresentation of an audio signal, wherein said digital coded audiospread spectrum transmitter is configured to wirelessly communicate witha digital audio spread spectrum receiver and is configured to be movedin any direction during operation, said wireless digital coded audiospread spectrum transmitter comprising: an encoder operative to encode afirst representation of an audio signal to reduce intersymbolinterference associated with a transmitted representation of the audiosignal, said encoder configured to process signals in the frequencyrange of 20 Hz to 20 kHz for representation in said first representationof an audio signal; a digital modulator configured to modulate the firstrepresentation of the audio signal, said digital modulator configured toperform a first modulation and a second modulation, said digitalmodulator configured to generate a second representation of the audiosignal, wherein said second modulation is differential phase shiftkeying (DPSK) modulation, and wherein said first modulation and saidsecond modulation are separate from encoding and processing by theencoder; and wherein the wireless digital coded audio spread spectrumtransmitter is configured to use the second representation of the audiosignal and to use independent code division multiple accesscommunication to wirelessly transmit a transmitted representation of theaudio signal, and wherein the transmitted unique user code distinguishesthe transmitted representation of the audio signal from othertransmitted audio signals in the spread spectrum transmitter spectrum,said other transmitted audio signals not originating from said wirelessdigital coded audio spread spectrum transmitter.
 6. The wireless digitalcoded audio spread spectrum transmitter of claim 5, wherein the firstrepresentation of an audio signal is representative of music.
 7. Thewireless digital audio spread spectrum receiver of claim 1, wherein saidfirst demodulation is 64-ary demodulation.
 8. The portable spreadspectrum receiver of claim 3, wherein said first demodulation is 64-arydemodulation.
 9. The wireless digital coded audio spread spectrumtransmitter of claim 5, wherein the first modulation is 64-arymodulation.